Several methods have been suggested as the method for producing an iron carboxylate (for example, Non-Patent Document 1 and Patent Document 1). These methods use iron salt compounds such as iron chloride and iron nitrate as raw materials. Furthermore, other methods include methods of dissolving metal powders in carboxylic acids (Patent Documents 2 and 3). In the iron carboxylates prepared by these other methods, since ion species of halogens and the like do not exist in large amounts with respect to iron, iron carboxylates of high purity can be obtained.